Downs made his first television news broadcast in September 1945 from the still experimental studio of WBKB-TV (now WBBM-TV), a station then owned by the Balaban and Katz theater subsidiary of Paramount Pictures.

On August 25, 1958, Downs concurrently began a more than ten-year run hosting the original version of the game show Concentration. Also, he hosted NBC's Today Show for nine years from September 1962 to October 1971, plus co-hosting the syndicated television program Not for Women Only with Barbara Walters in 1975–76. Downs also appeared as a panelist on the television game showTo Tell the Truth and in an episode, cast as himself, on the NBC police sitcom, Car 54, Where Are You?, set in New York City.[citation needed]

Downs earned a postgraduate degree in gerontology from Hunter College while he was hosting Over Easy, a PBS television program about aging that aired from 1977 to 1983. He was probably best known in later years as the Emmy Award-winning co-anchor — again paired with Walters — of the ABC news TV show 20/20, a primetime news magazine program, from the show's second episode in 1978 until his retirement in 1999.[citation needed]

Downs has been seen in infomercials for Bottom Line Publications, including their World's Greatest Treasury of Health Secrets, as well as another one for a personal coach. He did an infomercial for Where There's a Will There's an A in 2003. His infomercial work since then has aroused some controversy, with many arguing the products are scams.[5]

Downs has most recently appeared in regional public service announcements in Arizona, where he currently lives, for that state's Motor Vehicles Division; for Hospice of the Valley, a Phoenix-area non-profit organization specializing in hospice care, as well as in many public, short-form programs in which he serves as host of educational interstitials.[6]

Downs has expressed public praise for many libertarian viewpoints. He opposes the U.S. "war on drugs". He did several pieces about the war on drugs and hemp.[8] On his last 20/20 he was asked if he had any opinions of his own that he would like to express: he responded that marijuana should be legalized.[9]